1. Field
The present invention relates generally to wireless charging, and more specifically to devices, systems, and methods related to multi-dimensional wireless charging.
2. Background
Typically, each battery powered device requires its own charger and power source, which is usually an AC power outlet. This becomes unwieldy when many devices need charging.
Approaches are being developed that use over the air power transmission between a transmitter and the device to be charged. These generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and receive antenna on the device to be charged which collects the radiated power and rectifies it for charging the battery. Antennas are generally of resonant length in order to improve the coupling efficiency. This approach suffers from the fact that the power coupling falls off quickly with distance between the antennas. So charging over reasonable distances (e.g., >1-2 m) becomes difficult. Additionally, since the system radiates plane waves, unintentional radiation can interfere with other systems if not properly controlled through filtering.
Other approaches are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna plus rectifying circuit embedded in the host device to be charged. This approach has the disadvantage that the spacing between transmit and receive antennas must be very close (e.g. mms). Though this approach does have the capability to simultaneously charge multiple devices in the same area, this area is typically small, hence the user must locate the devices to a specific area.
When placing one or more devices in a wireless charger (e.g. near-field magnetic resonance, inductive coupling, etc.) the orientation between the receiver and the charger may vary. For example, when charging a medical device while disinfecting it in a solution bath or when charging tools while working under water. When a device is dropped into a container with fluid inside, the angle in which the device lands on the bottom of the container would depend on the way its mass is distributed. As another non-limiting example, when the charger takes the form of a box or a bowl, carelessly throwing the device into it, which is very convenient to the user, does not guarantee the position the device will end up in. The charger may also be integrated into a large container or cabinet that can hold many devices, such as a tool storage chest, a toy chest, or an enclosure designed specifically for wireless charging. The receiver integration into these devices may be inconsistent because the devices have different form factors and may be placed in different orientations relative to the wireless power transmitter.
Existing designs of wireless chargers may perform best under a predefined orientation and deliver lower power levels if the orientation between the charger and the receiver is different. In addition, when the charged device is placed in a position where only a portion of the wireless power can be delivered to it, charging times may increase. Some solutions design the charger in a way that the user have to place the device in a special cradle or holder that positions the device to be charged in an advantageous orientation, which is less convenient than placing it in the charger without thought, or one that cannot hold multiple devices.
Therefore, there is a need to provide systems and methods relating to multi-dimensional wireless charging.